- #1
laura_a
- 66
- 0
Homework Statement
[tex] int^{infty}_{0} \frac{x^3sinx}{(x^2+1)(x^2+9)} dx [/tex]
Homework Equations
I understand the value of the integral will be 2 * pi * [sum of residues]
and I am also aware of the formula
Res_{z=z_0} f(z) = [tex] \frac{g^{m-1} (z_0)}{(m-1)!} [/tex]
The Attempt at a Solution
I know the poles exsit and are x= + / - i and x = +/- 3i
only 2 in the countour and that is x=i and x=3i
so I get stuck here because all the examples have a bit of working out with a less than or equal to sign and an absolule value, which shows as it goes to zero R goes to inifity... I just don't understand how to set that bit up and why it is necessary, if you know what I'm talking about, can you please explain it to me?
Thanks
Laura